We don’t generally look to Game of Thrones for scientific consistency, though it’s noticeable when the series tests physics. One wouldn’t necessarily expect dragons to conform to said physics, but famed scientist Neil deGrasse Tyson actually has strong feedback for Season 7’s take on the mythical beasts.

You’re warned of Game of Thrones Season 7 spoilers from here on out, but whatever magical force compels dragons to up their size a full airplane class each year, producers put genuine thought into how the CG creatures actually move and fly. Astrophysicist and famed debunker Tyson even weighed in on the dragons over Twitter (a few weeks delayed, perhaps), noting that their biology was consistent with real science:

And while Season 7 didn’t take time to classify the exact undead status of Viserion, Tyson did note that the creature’s blue flame would be significantly hotter than that of his brothers, which could make for some interesting showdowns in Season 8:

All that said, Tyson was less enamored with the physics it took to get him out of that frozen lake in the first place: